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Don B. Arnold

Associate Professor

Molecular & Computational Biology
College of Letters Arts & Sciences

Don B. Arnold

Research Topics

  • Cellular Neurobiology
  • Membranes & Transport

Research Images

Fig. 1 (A) Live neuron in dissociated culture expressing intrabodies against PSD95 (green) and Gephyrin (red), which provide a real time map of synaptic inputs. PSD95 intrabody in dendrite of pyramidal cell in slice culture (B) or in dendrite of pyramidal cell in 45 day old mouse (C) that had been in utero electroporated.
Fig. 1 (A) Live neuron in dissociated culture expressing intrabodies against PSD95 (green) and Gephyrin (red), which provide a real time map of synaptic inputs. PSD95 intrabody in dendrite of pyramidal cell in slice culture (B) or in dendrite of pyramidal cell in 45 day old mouse (C) that had been in utero electroporated.
Fig. 2 (A) Schematic of ablating intrabody. (B) Neuron transfected with Gephyrin Intrabody-FRB and FKBP-E3 ligase domain. (C, D) 5 hours after addition of IRAP virtually 100% of endogenous Gephyrin is eliminated. Note that most, if not all, visible puncta in (C) and (D) are from untransfected cells.
Fig. 2 (A) Schematic of ablating intrabody. (B) Neuron transfected with Gephyrin Intrabody-FRB and FKBP-E3 ligase domain. (C, D) 5 hours after addition of IRAP virtually 100% of endogenous Gephyrin is eliminated. Note that most, if not all, visible puncta in (C) and (D) are from untransfected cells.

Research Overview

The work in my laboratory is focused on two broad areas.

(1) We study the molecular mechanisms underlying polarized targeting of proteins in neurons. We have discovered an actin- and myosin-based mechanism by which transmembrane proteins such as ion channels and receptors are targeted to either the surface of the axon or to the somatodendritic compartment. We showed that interaction with Myosin Va is both necessary and sufficient for the localization of dendritic proteins and Myosin VI plays a similar role in localization of proteins to the surface of the axon. We also showed recently that vesicles carrying dendritic or axonal proteins enter axons and dendrites with equal frequencies immediately following release from the Golgi apparatus. In the axon initial segment, however, vesicles carrying dendritic proteins almost all halt and some reverse in an actin- and Myosin Va-dependent manner, while vesicles carrying axonal proteins proceed to the distal axon. These results suggest that an actin-dependent vesicle filter is present in the AIS that mediates the selective trafficking of vesicles depending on their contents.

(2) We have developed recombinant probes known as intrabodies that can be used to label endogenous proteins in living neurons, or to mediate the degradation of endogenous proteins inducibly, specifically and very quickly. To make intrabodies we use mRNA display, an in vitro selection procedure developed by our collaborator Richard Roberts. We have used intrabodies to report the localization of endogenous proteins in neurons in dissociated culture, as well as in slices and in vivo following in utero electroporation. We have made intrabodies against PSD95, Gephyrin, CAM Kinase II and Kv4.2. When expressed in neurons intrabodies accurately report the localization and trafficking of target proteins without affecting their localization, expression level or function. Modified intrabodies known as ablating intrabodies can mediate the degradation of their endogenous target proteins inducibly, specifically, and very quickly. Ablating intrabodies mediate the direct ablation of their target proteins and, thus, work much faster than traditional, nucleic acid-based methods of protein degradation, such as RNAi. Furthermore, intrabodies are capable of specifically degrading proteins in particular conformations or with specific post-translational modifications. Thus, they could be used to specifically degrade pathological proteins involved in neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Huntington’s, without degrading wild-type forms of these proteins.

Contact Information

Mailing Address 2910 UPC
Office Location RRI 204B
Office Phone (213) 821-1266
Lab Location RRI. Rm 208
Lab Phone (213) 821-1818
Fax (213) 821-1818
Office Location RRI 204B

Websites

Education

  • B.A.Sc. University of Toronto, 1986.
  • Ph.D. John Hopkins University, 1992.
  • Postdoctoral Fellow, Rockefeller University 1992-1997.
  • Postdoctoral Fellow, Harvard University 1997-1999.

Selected Publications

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  • Al-Bassam, S., Xu, M., Wandless, T.J., and Arnold, D. B. Differential trafficking of transport vesicles contributes to localization of dendritic proteins. in press Cell Reports.
  • Lewis, T.L. Jr., Mao, T, and Arnold, D. B. (2011) A role for Myosin VI in localization of axonal proteins. PLoS Biology e1001021. PMID:21390300 PubMed Link
  • Arnold DB. (2009) Actin and microtubule-based cytoskeletal cues direct polarized targeting of proteins in neurons. Science Signaling, 2(83):pe49. PubMed
  • Lewis TL Jr, Mao T, Svoboda K, Arnold DB. (2009) Myosin-dependent targeting of transmembrane proteins to neuronal dendrites. Nat Neurosci.12(5):568-576. PubMed
  • Chu PJ, Rivera JF, Arnold DB. (2006) A role for Kif17 in transport of Kv4.2. J Biol Chem. 281(1):365-373. PubMed
  • Arnold DB. (2007) Polarized targeting of ion channels in neurons. Pflugers Arch. 453(6):763-769. PubMed
  • Rivera, J. F., Ahmad, S., Quick, M. W., Liman, E. R., and Arnold, D. B. (2003) An evolutionarily conserved dileucine motif in Shal K+ channels mediates dendritic targeting. Nat Neurosci. 6(3):243-250. PubMed
  • Arnold DB. (1999) Clapham DE Molecular determinants for subcellular localization of PSD-95 with an interacting K+ channel. Neuron 23(1):149-157. PubMed
  • Tao X, Finkbeiner S, Arnold DB, Shaywitz AJ, Greenberg ME. (1998) Ca2+ influx regulates BDNF transcription by a CREB family transcription factor-dependent mechanism. Neuron 20(4):709-726. PubMed
  • Arnold DB, Heintz N. (1997) A calcium responsive element that regulates expression of two calcium binding proteins in Purkinje cells. Proc Natl Acad Sci USA 94(16):8842-8847. PubMed